Antioxidants and Prostate Cancer: Friends or Enemies?

Study reviews controversial subject of antioxidant use for treatment and prevention

Once deemed a “harmless” cancer, a cancer you live with but don’t die from, prostate cancer is being given a second look. The male counterpart to ovarian cancer, prostate cancer affects 1 in 6 men in the United States.

Every year, nearly a quarter of a million men (240,890) are diagnosed with prostate cancer, and 14 percent of those will die from the disease. This makes prostate cancer the second leading cause of cancer death among American men, behind lung cancer.

Rather sobering statistics for a “harmless” cancer.

While there are many factors that increase your risk that are out of your control (genetic links and certain environmental factors), there is one thing that you do have direct control over: your diet.

One area of diet has drawn much attention as it relates to prostate cancer prevention, and that is antioxidants. One side of the aisle feels that antioxidants are beneficial for both treating and preventing prostate cancer. The other side feels that antioxidants are downright dangerous and can actually lead to prostate cancer. Then, of course, there are those that feel antioxidants have no effect either way.

So who’s right? According to Texas researchers, everyone.[1] Let me explain.

Understanding Prostate Cancer

There are many factors that contribute to prostate cancer. The most direct are androgens, which are steroid hormones that are responsible for the development of masculine characteristics. Therefore, many medications for prostate cancer involve blocking androgens. These are often referred to as androgen-deprivation therapy or ADT.

Next, there is oxidative stress. We’ve discussed this many times before in previous articles. A variety of things can trigger oxidative stress, including aging, inflammation, stress, radiation and certain chemicals.

Within your body, certain molecules called reactive oxygen species (ROS) are the product of oxidative stress. The greater the oxidation within your body, the more ROS you have.

Several studies have shown that the greater the oxidative stress in your body and the higher your levels of ROS, the greater your risk for developing prostate cancer. It also increases your risk for speeding up the growth and possible metastasizing of the disease.

Next comes inflammation. In fact, inflammation and oxidative stress have been shown to go hand-in-hand. And inflammation and prostate cancer have also been found to go hand-in-hand.

Now here’s where it gets tricky. Several animal studies have shown that there is a connection between oxidative stress and androgen signaling. More directly, there is a school of thought that blocking androgens (as you do with ADT) can actually increase oxidative stress.

This is bad news, as it infers that treating one cause of prostate cancer may actually trigger a different risk factor. Not good.

The Pro-Antioxidant Movement

Fortunately, antioxidants have long been known to protect against oxidative stress, as well as inflammation. Of these, lycopene, selenium, beta-carotene, vitamin E, curcumin, resveratrol, green tea and genistein (a soy isoflavone) are the most promising.

Lycopene in particular has been found to inhibit tumor growth. Ditto for beta-carotene.

Nutrients such as curcumin and resveratrol have been heralded in particular for their anti-inflammatory benefits, while the active ingredient in green tea (EGCG) has been shown to inhibit early-stage prostate cancer.  

The Nutritional Prevention of Cancer trial and the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study found that selenium-treated yeast yielded a 63 percent reduction in prostate cancer, while vitamin E (as alpha-tocopherol) boasted a 32 percent reduction.

When it comes to lycopene, one study found that 10 mg a day of lycopene in capsule form was not only safe, but effective. As for green tea, research has shown that 600 mg of green tea catechins a day decreased prostate cancer incidence, with just 3 percent of the green tea group developing prostate cancer as opposed to 30 percent in the placebo group.

The Anti-Antioxidant Movement

However, the news isn’t all good. One large study, the Selenium and Vitamin E Cancer Prevention Trial (SELECT) found that 200 mcg of selenium (as selenomethionine) daily, when given to men age 50 or older, did not prevent prostate cancer. This same study also found that 400 IU a day of vitamin E actually increased the risk of prostate cancer in healthy men.

In fact, several studies have shown that large doses of antioxidants can increase cancer risk. As the researchers point out, the key here is “large dosages.” In the SELECT study, the men took 13 times the recommended dosage of vitamin E and three times the RDA for selenium.

They stated, “It is safe to conclude that there is no evidence that suggest that consuming recommended dosage of antioxidants increases cancer risk.”

They also indicate that antioxidants are micronutrients and are meant to act in conjunction with other nutrients versus in isolation. Lastly, they state that early intervention seems to be key when it comes to antioxidants’ benefits for prostate cancer prevention.

They conclude, “Dose and choice of antioxidants as well as criteria and age of intervention may hold the key to lack of clinical validity.”

Make a Move

After looking over these studies, I would recommend a few things. First and foremost, get the bulk of your antioxidants from foods, particularly fruits and vegetables. This will provide safe yet effective levels while also providing critical other micronutrients.

Tomatoes in particular are critical for men with prostate cancer due to their lycopene content. Just be sure to cook the tomatoes in olive oil to increase the bioavailability of the lycopene.

Next, get to know green tea. Aim for at least two eight-ounce, unsweetened cups of green tea a day.

Finally, when it comes to supplementation, stick with recommended dosages rather than the mega doses. This is especially critical when it comes to vitamin E.


[1] Thapa D and Ghosh, R. Antioxidants for prostate cancer chemoprevention: challenges and opportunities. Biochem Pharmacol. 2012 Jan 11. [Epub ahead of print.]

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